[GitHub] [calcite] DonnyZone commented on a change in pull request #1981: [CALCITE-4000] Support OFFSET parameter in TUMBLE/HOP table functions…

[GitBox <gi...@apache.org>]

DonnyZone commented on a change in pull request #1981:
URL: https://github.com/apache/calcite/pull/1981#discussion_r453469608



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File path: core/src/main/java/org/apache/calcite/adapter/enumerable/RexImpTable.java
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@@ -3406,9 +3406,23 @@ abstract Expression implementSafe(RexToLixTranslator translator,
       translatedOperands.add(wmColExpr);
       translatedOperands.add(intervalExpression);
 
-      return Expressions.call(BuiltInMethod.TUMBLING.method, inputEnumerable,
-          EnumUtils.tumblingWindowSelector(inputPhysType, outputPhysType,
-              translatedOperands.get(0), translatedOperands.get(1)));
+      // handle the optional offset parameter.
+      if (call.getOperands().size() > 2) {
+        translatedOperands.add(translator.translate(call.getOperands().get(2)));
+      } else {
+        // use 0 for the default value when offset parameter is not set.

Review comment:
       Can we simpilfy this logic as below? It may be more intuitive.
   ```
   // handle the optional offset parameter, use 0 as default when ...
   final Expression xxxExpression = call.getOperands().size() > 2 ? translator.translate(call.getOperands().get(2)) : Expressions.constant(0, long.class);
   translatedOperands.add(xxxExpression);
   ```




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